A wireless local area mesh network consists of multiple nodes (also called mesh points) interconnected via IEEE 802.11 radio links. Each node has its unique IEEE 802.11 Media Access Control (MAC) address. A subset of nodes in the mesh network may join a multicast group to communicate with each other. A multicast group has its own group IEEE 802.11 MAC address for communications among the multicast group members. Multicast offers efficient utilization of network resource to deliver data from a source to multiple destination nodes (multicast group). For example, a number of nodes in the mesh network might join a multicast group for video conferencing. When a member node in a multicast group sends the data to all other member nodes, it uses the multicast group's common IEEE 802.11 MAC address as the destination address. The multicast group membership information, i.e. which nodes are members of the multicast group, is required to establish the paths/routes between the members of the multicast group in a wireless mesh network and to deliver the data.
The IP layer multicast routing protocols have been used to discover and establish the routes for a multicast group in wired and wireless networks. However, the IP layer multicast routing protocols are based on the IP addresses. Some of devices, such as wireless local area network (WLAN) access points, forward data packets based on the IEEE 802.11 MAC address and only operate at the link layer (Layer 2). In addition, data forwarding at Layer 2 is generally faster than that at the IP layer (Layer 3) because the data packet does not have to pass to the IP layer. Therefore, multicast mesh routing mechanisms at layer 2 are needed to forward data among the members of a multicast group based on the multicast group's IEEE 802.11 MAC address in wireless mesh networks.
The Protocol Independent Multicast-Sparse Mode (PIM-SM) and the Protocol Independent Multicast-Dense Mode (PIM-DM) are two standard IP multicast routing protocols. PIM-DM employs a flooding and then pruning approach, which results in large overhead. PIM-SM employs a join/prune approach, which is more efficient in terms of network resource utilization. However, PIM-SM is designed for wired Internet and requires manual configurations such as configuration of the static multicast group address-to-root address mapping in every node or configuration of a bootstrap server in the network to announce this mapping. Manual configurations are not well suited for dynamic mesh networks since the network may be formed in an ad hoc fashion and the network nodes/topology frequently change. As nodes join and depart from the mesh network the topology changes.
What is needed is a multicast mesh routing protocol for wireless local area mesh networks to discover and establish the paths among the multicast group members for communications based on the multicast group's IEEE 802.11 media access control addresses. The problem solved by the present invention is how to efficiently establish the multicast routes and forward the data from any member node in the multicast group to all other members based on the multicast group's IEEE 802.11 MAC address.